A Low-Cost and Accurate Method for Measuring Weak Magnetic Susceptibilities

BONIN, CLAUDIO J.; BONETTO, FERNANDO J.

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Año: 2022 vol. 71 p. 1 - 10

0018-9456

The magnetic properties of any substance in nature can be condensed in a unique parameter: the volume magnetic susceptibility . Its value and sign indicate if a given material is diamagnetic, paramagnetic or ferromagnetic. Accurate measurements of  for paramagnetic or diamagnetic substances are generally performed with high-tech devices with relatively complex methods. Simple methods proposed to determine  for everyday materials result in inaccurate measurements (≥ 50 %). Here we propose a simple, practical and low-cost method to accurately obtain , via measurements performed with an ordinary balance and a set of neodymium magnets. The force exerted by the magnets on a given sample is sensed by the balance and, via comparison with exact numerical calculations of the magnetic force on the whole sample, the magnetic susceptibility can be determined. The shape, size and position of the sample relative to the magnets as well as the number of neodymium magnets are optimized to maximize the magnetic force on the sample and, therefore, minimize the experimental uncertainties in the determination of .